Assessment of the AquaCrop Model for Simulating Maize Response to Different Nitrogen Stresses under Semi-arid Climate

AquaCrop applies an automatic calibration procedure through semi-quantitative approach to determine degree of soil fertility stress on crop production and water productivity. The objective of this study was to assess this capability of AquaCrop to simulate maize grain yield and biomass production, canopy cover and soil water content in the root zone under different nitrogen (N) applications in a semi-arid environment. The field experiments were conducted at the research farm located in Tehran, over the 2015 and 2016 growing seasons. Five N treatments were investigated including no nitrogen (N0), 50(N1), 100(N2), 150(N3) and 200 kg N. ha(-1) (N4) for each year. Calibration was carried out using the data of N0 and N4 in 2015 and validation in the field was performed with remaining data. The results indicated that the range of relative root-mean-square error (RRMSE), coefficient of determination (R-2) and mean bias error (MBE), for estimating final biomass production were obtained as 5.16%, 0.966, 0.28 ton. ha(-1), and for final grain yield were 14.64%, 0.939, 0.56 ton. ha(-1), respectively. The AquaCrop simulated canopy cover and biomass production development with RRMSE of 16.23-24.12% and 6.09-32.39%, respectively. The performance of the model for simulating soil water content was also good with RRMSE< 10.78%. Over all, these results confirmed that the AquaCrop model could be an applicable tool for managing maize production under different N stresses in a semi-arid environment.